I am in the process of calculating the hydrogen ion concentration in a .25litre solution of sulfuric acid,.21g of sulfuric acid was disolved in water to make the solution. I have calculated the molarity of the acid to be 2.14x10^-3 mol per litre.
I also need help in calculating the pH of the acid soulution.

Well, if the H ion is twice that concentration..

pH= -log(2*2.14*10^-3)
grab your calculator.

I think you should check your calculations. I THINK you have 0.21/98 = 2.14 x 10^-3 mols but that is in 0.25 L. You want mols/L.

I have calculated the mols/L by multiplying .25ltrs and .21g by 4. This gives .84mols per litre. can this be confirmed for me please.